Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Recently, technology for purifying indoor air has attracted public attention in accordance with the increase of contemporary airtight houses and buildings and widespread viruses hazardous to human health, such as SARS and influenza viruses. This has led to active research for improving indoor conditions by removing microparticles in air, such as cigarette smoke and pollen, and hazardous gases, such as volatile organic compounds (VOCs).
Air purifiers that are widely used have a common structure, which intakes indoor air and removes microparticles in the air with filters. Many of these filters include “solid” filters, which may be activated charcoal and/or high efficiency particulate air (HEPA) filters which is a type of air filter that satisfies standards of efficiency set by the United States Department of Energy (DOE). In these purifiers, the filters themselves are expensive and have to be periodically replaced in order to sustain the performance, and thus, they can be costly to operate. Alternatively, air purifiers using liquid, such as water, which removes pollutants in the air, have been proposed. These purifiers are able to remove hazardous gases, VOCs, etc., in addition to dust, cigarette smoke, viruses, and bacteria. Thus, these purifiers can be more versatile than the “solid” filters.
Air purifiers using liquid can be classified into two types, based on their operating principle. One is a spray type which involves spraying liquid into air, and the other is a bubble type which involves dispersing air into liquid as air bubbles.